updated status of the maribojoc bay mangrove forest, bohol...

Calumpong et al. (2016). Mangroves of Maribojoc Bay

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Updated Status of the Maribojoc Bay Mangrove Forest, Bohol, Philippines

Hilconida P. Calumpong1, Dianne Mira Yap1, Claro Renato Jadloc1,

AndrianiRafael1, John Michael Arellano1, Maribel Acierto2, and Emelinda Roslinda2

1Institute of Environmental and Marine Sciences, Silliman University

Dumaguete City, Philippines 6200 2PROCESS-Bohol, Tagbilaran City, Bohol

Introduction

In a survey conducted in 1997 (SUML, 1997), 25 mangrove species in 13 families were recorded from 3 (deLa Paz, Lincod, San Vicente) barangays in Maribojoc Bay. One of the barangays (San Vicente) was revisited in 2013 and an additional 2 barangays (Upper de la Paz, Dipatlong) were further surveyed adding 7 species to the list but 6 species were not seen (PROCESS-FPE, 2013). The 7 new records include the endangered Camptostemon philippinensis (IUCN, 2016), locally called ‘gapas-gapas’. This resurvey was requested by PROCESS-Bohol to confirm the species composition of the mangroves fringing Maribojoc Bay with a view towards establishing the area as a “living ecological museum”. Generally, the project aims to gather data as basis for stronger legislation to protect the mangrove forest ecosystem in Maribojoc Bay and formulation of a management plan to address its degraded condition as reported by PROCESS-Bohol. Specifically, the project aimed at(1) verifying the presence of the seven new records of mangrove species as well the 6 species not seen in 2013 ; (2) mapping the location of the species; (3) determining tree sizes (diameter at breast height) and abundance (in terms of tree counts per species); (4) training local community researchers in basic mangrove taxonomy. Expected outputs of this resurvey include (1) species list, species location (GPS way points), average size per species, density per species per barangay; (2) Georeferenced map per species for the whole Maribojoc Bay; and (3) at least 4 mangrove parataxonomists trained per barangay.

Methods

Training. On the job training was the strategy used. Local community researchers

participated in a one-day lecture workshop on mangrove taxonomy and methods of

assessment, after which the trainees undertook the assessment of their assigned barangay

under the tutelage of an SU researcher. Trainees were given mangrove photoguides to help

them in the identification. Each species encountered was georeferenced, photographed and

measured. When the survey was completed, the whole group validated the results.

Assessment. Pre-mapping, based on the 1997 and 2013 surveys, was done by SU researchers

prior to the survey to determine sites to be sampled. The Bay was then divided into four

barangays, each barangay assigned to one SU researcher and 4 trainees. Two samplings were


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conducted, one in May 2016, the other in October 2016. Sampling was purposive, i.e., each

team set out to find species in the list. A GPS device was used to mark the location of species

found and waypoints mapped using Surfer. The plot method of English et al. (1997) was used

to determine density of mature trees, seedlings and saplings per species and diameter at

breast height (dbh). A caliper was used to measure diameter at breast height (DBH) but for

large trees, girth at breast height (gbh) was taken using a tape measure and the resulting

value was divided by pi (3.1416) to get DBH. All mature trees within a 10 x 10 m plot were

identified, counted, photographed, and measured. Saplings (<4 cm in dbh, >1 m tall) were

identified and counted with a 5 x 5 m plot. Seedlings (<1 m tall) were identified and counted

with 1 x 1 m plot. Fauna seen in the area were noted as well threats to mangrove ecosystems

such as garbage, new fishponds, reclamations, etc.

Results

Training. Sixteen members of four peoples’ organizations completed the training on Mangrove Taxonomy and Assessment. The list of trainees and their PO affiliation is found in Annex 1. Lectures and practice were conducted on Day 1 at the Abatan Tourist Center in Cortes (see Annex 2-3). The training module consisted of the following topics: 1) What are mangroves and what are the services and goods that they provide? 2) How do we identify mangrove species? 3) How do we assess mangroves? 4) How do we do mangrove mapping? During the first sampling the actual field surveys and mapping were done on Days 2 and 3 (see Annex 5) while validation of data and closing ceremonies were completed on Day 4 (see Annex 5).

Survey Sites. Six barangays (de la Paz, Upper de la Paz in Cortes, Lincod, Cabawan, San

Vicente, Dipatlong in Maribojoc) in two municipalities (Cortes, Maribojoc) were surveyed (Fig.

1). The survey tracks and plots are shown in Figure 2.

Figure 1.Barangays surveyed in Maribojoc Bay, Bohol.


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Three sites were assessed in 1997: de la Paz, Lincod and San Vicente; de la Paz was not was

reassessed in 2013 but Dipatlong, and Upper de la Paz were added while a new site

(Cabawan), was added in 2016 but only the site along the Abatan River was surveyed.

Figure 2A. Survey tracks in Upper de la Paz and de La Paz (top) and Lincod (bottom).


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Figure2B. Survey tracks in San Vicente (top) and Dipatlong (bottom).


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Species Composition. A total of 35 mangroves in 15 families, including one hybrid, and 20

associated species in 17 families (excluding unidentified ones) were identified in the area

(Table 1). Three new records in three families are added to the list; Heritiera littoralis Dryand.

(Malvaceae), Scyphiphora hydrophyllacea Gaerten. f. (Rubiaceae), and Xylocarpus rumphii

(Kostel) Mabb (Meliaceae). The first one was found only in Cabawan while the last two were

found only in San Vicente. Photos of all species, including the associates are found in Plate 1.

Mangrove classification follows the scheme found in Massó et al. (2010). It should be noted

that under this scheme, 4 species originally put in the true mangrove list are transferred to

the mangrove associates category. These are Barringtonia asiatica (L.) Kurz, Derris trifoliata

Lour., Dolichandrone spathacea (L.) K. Schum., Pongamia pinnata (L.) Pierre. Also, three

families are merged, Aviceniaceae with Acanthaceae, Myrsinaceae with Primulaceae and

Lythraceae with Sonneratiaceae.

Four species are in the IUCN (2015) threatened species list: Aegiceras floridum Roem. and

Schult.–Near Threatened ver. 3.1, Avicennia lanata Ridley– Vulnerable B1+2c ver 2.3,

Camptostemon philippinensis (S.Vidal) Becc.– Endangered C1 ver. 3.1 and, Ceriops decandra

(Griff.) Ding Hou– Near Threatened ver. 3.1.

All sites had increased number of species over the 2013 survey, except Upper de la Paz with

six less species seen in 2016. Dipatlong had the most dramatic increase, from 7 species in

2013 to to 26 species in this current survey. The breakdown per barangay is given in Table 1.

Figure2C. Survey tracks along Abatan River.

http://www.iucnredlist.org/static/categories_criteria_2_3


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This could be due to the more systematic search conducted. Three species were found only

in San Vicente: Xylocarpus rumphii (Kostel) Mabb. (Meliaceae), Scyphiphora hydrophyllacea

C.F.Gaertn. (Myrtaceae) and Aegiceras floridum Roem.& Schultes (Myrsinaceae), although

the latter was recorded in Upper de la Paz in 2013 but not found there during this survey. The

endangered Camptostemon philippinensis was not seen in the areas surveyed in San Vicente

but was found in Lincod. This may be because the stations surveyed in 2013 were not the

same as the one in the current survey as no specific locations of survey stations were given in

the 2013 report. Three species were not seen in this current survey and were put on the

watch list: Acanthus ilicifolius, Sonneratia caseolaris (L.) Engler., and S. ovata Backer. This is

because we rely on the flowers/fruits for the species confirmation and it was not their

flowering/fruiting period.

Eight species in 5 families were found in all sites, Avicennia marina (Forsk.) Vierh.

(Acanthaceae), Excoecaria agallocha L. (Euphorbiaceae), Nypa fruticans (Thun.) Wurmb

(Arecaceae), 4 species in the Rhizophoraceae –Ceriops decandra (Griff.) Ding Hou, Rhizophora

apiculate Blume, R. mucronata Lamk., R. stylosa Griffith, and Sonneratia alba J. Smith

(Lythraceae).

Based on local knowledge, the unidentified mangrove in 1997 locally called “maudo” was

identified as Lumnitzera littorea (Jack) Voigtand the unidentified fern, Acrostichum speciosum

Willd. “Tungki” is not a mangrove species but the local name for the propagules of

Rhizophora.

Based on studies conducted at SU-IEMS (unpub.), Acanthus ebracteatus Vahl. and A. ilicifolius

L. can change leaf morphology depending on exposure to sunlight and can take the form of

A. volubilis Wall. We have retained Acanthus ebracteatus in this listing.

One hydrid was identified: Rhizophora x lamarckii Montr. (R. stylosa x R. apiculata).

Table 1. Mangrove species identified in Maribojoc Bay. Totals are per sampling.

Legend: X = 1997; / = 2013; + = 2016; NS = not surveyed; () =total to date.

Abbrev: PAZ = De la Paz; UPA = Upper de la Paz; LIN = Lincod; VIC = San Vicente; DIP

= Dipatlong; CAB = Cabawan; DD = Data Deficient; EN = Endangered; LC = Least

Concern; NT = Near Threatened; V = Vulnerable; NA = Not Assessed Species Family Local Name IUCN PAZ UPA LIN VIC DIP CAB

1 Acanthus ebracteatus Vahl

Acanthaceae Lagiwliw-puti LC + + /+ +

2 Acanthus ilicifolius L. Acanthaceae Diliuatiao/Lagiwliw LC X / /

3 Acanthus volubilis Wall. Acanthaceae Ragoyroy LC / /

4 Acrostichum aureum L. Pteridaceae Paku-laut/Lagolo LC + + +

5 Acrostichum speciosum Willd.

Pteridaceae Paku-laut/Lagolo LC X+ + X+ +


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Species Family Local Name IUCN PAZ UPA LIN VIC DIP CAB

6 Aegiceras corniculatum (L.) Blanco

Primulaceae (=Myrsinaceae)

Saging-saging LC X+ / + X/+ +

7 Aegiceras floridum Roem. and Schultes

Primulaceae (=Myrsinaceae)

Tinduk-tindukan/ NTver

3.1 X +

8 Avicennia lanata Ridley Acanthaceae

(=Avicenniaceae) Api-api

VuB1+

2c ver 2.3

+ + + +

9 Avicennia marina (Forssk.) Vierh.

Acanthaceae (=Avicenniaceae)

Piapi/Bungalon LC X+ /+ X+ X/+ /+

10 Avicennia officinalis L. Acanthaceae

(=Avicenniaceae) Api-api/Piapi LC + /+ X+ X/+

11 Avicennia rumphiana Acanthaceae

(=Avicenniaceae) /

12 Bruguiera cylindrica (L.) Blume

Rhizophoraceae Pototan-lalake LC + / +

13 Bruguiera gymorrhiza (L.) Lamk.

Rhizophoraceae Busaing LC / X +

14 Bruguiera parviflora Wight & Arnold ex Griffith

Rhizophoraceae LC X+ /+ +

15 Bruguiera sexangula (Lour.) Poir.

Rhizophoraceae Pototan LC / +

16 Camptostemon philippinensis (S. Vidal) Becc.

Malvaceae Gapas-gapas

EN C1

ver. 3.1

+ /

17 Heritiera littoralis Dryand.

Malvaceae Dungon +

18 Ceriops decandra (Griff.) Ding Hou

Rhizophoraceae Malatangal/Lapis-

lapis

NT ver. 3.1

X+ /+ X+ X/+ +

19 Ceriops tagal (Perr.) C.B. Rob.

Rhizophoraceae Tungog LC X+ + /+

20 Excoecaria agallocha L. Euphorbiaceae Alipata/Buta-buta LC + /+ X+ /+ +

21 Lumnitzera racemosa Willd.

Combretaceae Kulasi LC + / + X+

22 Lumnitzera littorea (Jack) Voigt

Combretaceae Tabao/Maudo LC +

X+ +

23 Nypa fruticans (Thun.) Wurmb

Arecaceae Nipa LC X+ /+ X+ X/+ /+

24 Osbornia octodonta F. Mueller

Myrtaceae Tawalis LC + + /+

25 Rhizophora apiculata Blume

Rhizophoraceae Bakhauan-laki LC X+ /+ X+ /+ /+

26 Rhizophora mucronata Lamk.

Rhizophoraceae Bakhauan-baje LC X+ /+ X+ /+ /+

27 Rhizophora stylosa Griffith

Rhizophoraceae Bakauan/Bakhawan-

tigrihon LC + /+ + /+ +

28 Rhizophora x lamarckii Montr.

Rhizophoraceae Hybrid bakauan LC + +

29 Scyphiphora hydrophyllacea C.F.Gaertn.

Rubiaceae Nilad LC +

30 Sonneratia alba J. Smith Lythraceae

(=Sonneratiaceae) Pagatpat LC X+ /+ + X/+ /+

31 Sonneratia caseolaris (L.) Engler

Lythraceae (=Sonneratiaceae

Pagatpat LC X / X

32 Sonneratia ovata Backer Lythraceae

(=Sonneratiaceae Pagatpat NT / / /


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Species Family Local Name IUCN PAZ UPA LIN VIC DIP CAB

33 Xylocarpus granatum König

Meliaceae Tabigi LC /+ X+ +

34 Xylocarpus moluccensis (Lamk.) Roem.

Meliaceae Tabigi/Piagau LC + + X/ +

35 Xylocarpus rumphii (Kostel) Mabb.

Meliaceae Tabigi/Piagau LC +

SUBTOTAL 13/17

21/15 10/21

9/16/21

7/19 2

B. Mangrove Associates

1 Barringtonia asiatica (L.) Kurz

Lecythidaceae Bitobitoon LC + X+

2 Calophyllum inophyllum L.

Clusiaceae Bitaug LC + +

3 Cordia subcordata Lamk. Boraginaceae Agutug LC +

4 Corypha utanLamk. Arecaceae Buli LC +

5 Derris trifoliataLour. Fabaceae Tuble NA + X+ + +

6 Dolichandrone spathacea (L.) K. Schum.

Bignoniaceae Tui LC X X +

7 Ficus cumingii Miq. Moraceae NA + +

8 Finlaysonia maritima Back. ex K. Heyne (=F. obovata Wall.)

Asclepediaceae NA +

9 Gymnanthera oblonga (Burm. f) P.S. Green

Apocynaceae Bagon NA +

10 Hibiscus tiliaceusL. Malvaceae Malobago +

11 Ipomea-pescapre (L.) R. Brown

Convolvulaceae NA +

12 Morinda citrifolia L. Rubiaceae Noni NA + +

13 Pandanus tectorius F. Brown

Pandanaceae Pandan DD +

14 Premna odorata Blco. Verbenaceae Abgao NA + +

15 Pongamia pinnata (L.) Pierre

Fabaceae Bani/Bawok-bawok LC X/+ +

16 Prosopis juliflora (Swartz) DC.

Fabaceae Aroma +

18 Sesuvium portulacastrum (L.) L.

Aizoaceae Olasimang-dagat NA + +

19 Sterculia ceramic R. Brown

Sterculiaceae Owas/ NA +

20 Terminalia catappa L. Combretaceae Talisay NA + + + +

21 Unidentified sp.1 X

22 Unidentified sp.2 X

23 Lumboy-lumboy X

24 Bagon-bagon X

SUBTOTAL 1/3 0 7/12

1/1/8

7 2

OVERALL TOTAL 14/20

21/15 17/33

11/18/29

7/26 2

Community Structure. The mangrove forest of Maribojoc Bay is a combination of natural and

reforested areas. Reforested areas are generally planted to Rhizophora stylosa and these are

found in the seaward portion of the forest. The river banks are fringed with Nypa fruticans

with its associated fern species (Acrostichum). Landward is where most of mangrove


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associates are found. Large areas, are still protected, e.g., in San Vicente but in Lincod, only

a small portion is left as most of it has been converted to fishponds.

Density. The most common species is Sonneratia alba as shown in Fig. 3 with mean density

of 318 + 317 stems ha-1. This is followed by Rhizophora apiculata and R. stylosa with mean

densities of 229 + 228 and 2221 + 378 stems ha-1, respectively. Avicennia marina ranked

fourth with a mean density of 137 + 113 stems ha-1. The large standard deviations is are due

to the clumped distribution of mangrove species. Five species had mean densities between

100-50 stems ha-1while 11 species had mean densities below 50 stems ha-1. Only one stem

was found in the surveyed plots for the following species: Aegiceras floridum, Bruguiera

gymnorrhiza and Xylocarpus rumphii. For Lumnitzera racemosa, only the shrubby form was

seen.

For shrubby and herbaceous mangrove species, these were quantified using per cent cover

(see Table 2). Nypa fruticans had mean cover of 42.0 + 36.3%, the mangrove ferns

(Acrostichum spp.) had a combined average cover of 3.7 + 9.8%, Derris trifoliata covered 1.5

+ 6.9 while Acanthus ebracteatus covered only 8.7 + 24.8 %. The large standard deviations are

due to plots without presence of the species (zero values) while Nypa and its associated ferns

are found only along riverbanks.

Table 2. Per cent cover of shrubby and herbaceous mangrove species in Maribojoc Bay

Bohol.

Species % Cover

1. Nypa fruticans 42.0 + 36.3

2. Acanthus ebracteatus 8.7 + 24.8

3. Acrostichum aureum 0.5 + 3.4

Figure 3. Density of mangrove tree species in Maribojoc Bay.

0

100

200

300

400

500

600

700

Nu

mb

er o

f st

ems

per

ha

Species


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4. Acrostichum speciosum 3.1+ 9.4

5. Derris trifoliata 1.5 + 6.9

Regeneration potential. Of the more than 30 species of mangroves, seedlings/saplings of 19

species and 1 associated species were seen (see Fig. 4).This gives a regeneration potential of

about 50%. Bruguiera parviflora had the highest number of seedlings (2605 + 5414 seedlings

ha-1) but almost no saplings were found (1 + 2 saplings ha-1) while Ceriops decandra had the

most number of saplings (902 + 1057 saplings ha-1) but no seedlings were seen. No seedlings

were seen for 4 species with saplings and no saplings were seen for 5 species with seedlings.

Relative Density and Size

Figure 4. Density of seedlings and saplings.

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

Nu

mb

er o

f st

ems

per

ha

Seedlings Saplings


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De la Paz. De la Paz was surveyed in 1997 but not in 2013. The two plots visited in 1997 were

revisited in 2016 (see suvey tracks in Fig. 2A). Twenty species were seen, an increase of 6

species over the previous survey. Based on relative density Rhizophora apiculata was the

most abundant in the seaward portion while Avicennia officinalis was the most abundant in

the landward portion of the forest (see Fig. 5). Biggest trees were Avicennia lanata, found in

the seaward portion (see Table 3) with maximum diameter at breast height (DBH) of 41.4 cm

and average basal area (BA) of 1114.9 cm2.

Table 3. Minimum, maximum and average DBH and basal area (BA) of mangrove trees in surveyed plots in de la Paz.

Species Min DBH (cm)

Max DBH (cm)

Average DBH (cm)

Average BA

(cm2)

Avicennia lanata 33.1 41.4 37.6 1114.9

Avicennia marina 5.1 19.1 13.8 164.8

Rhizophora apiculata 4.5 19.4 10.7 107.5

Sonneratia alba 28.6 35.0 31.8 803.7

Upper de la Paz. Upper de la Paz was not surveyed in 1997 but surveyed in 2013 and 2016.

Area surveyed was mostly along the Abatan River (see Fig 2A). Thirteen species were seen, a

decrease of seven species over the previous survey. Noteworthy was Bruguiera sexangula

which was not seen in this survey but was seen up River in Cabawan area. One plot along

Figure 5. Relative density of mangrove species in de la Paz and Upper de la Paz.


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Abatan River was monospecific with large trees of Bruguiera parviflora. This is the only site

where large trees of Lumnitzera littorea were found but were also threatened by girdling (see

Fig. 10).

Based on relative density Rhizophora apiculata was still the most abundant in the seaward

portion while four species formed monospecific patches in the landward portion and along

riverbanks: Sonneratia alba, Bruguiera parviflora, Xylocarpus moluccensis and Excoecaria

agallocha (see Fig. 5). Biggest trees were Sonneratia alba found along Bacong River (see Table

4),with maximum DBH of 51.6 cm and average BA of 543.2 cm2. There were also big trees of

Avicennia marina (maximum DBH of 39.8 cm) in the seaward portion of the forest.

Table 4. Minimum, maximum and average DBH and basal area (BA) of mangrove trees in

surveyed plots in Upper de la Paz. Species Min DBH Max DBH Average DBH Average BA (cm2)

Avicennia marina 4.1 39.8 11.4 139.1

Avicennia officinalis 10.8 31.5 19.6 362.4

Bruguiera parviflora 5.1 28.6 10.9 114.8

Bruguiera cylindrica 5.4 9.2 7.9 50.8

Ceriops decandra 4.8 6.7 5.7 26.5

Ceriops tagal 10.2 13.1 11.6 107.6

Excoecaria agallocha 4.5 33.1 14.7 247.7

Lumnitzera littorea 5.1 17.5 11.8 120.5

Rhizophora apiculata 4.8 29.6 10.5 99.6

Rhizophora stylosa 5.0 14.0 8.1 58.3

Sonneratia alba 6.4 51.6 23.2 543.2

Xylocarpus moluccensis 11.8 23.9 14.9 195.1

Xylocarpus granatum 24.5 24.5 1 tree only 471.8

Dipatlong. Among all sites, Dipatlong showed highest increase in the number of species, from

7 in 2013 to 19 in the current survey. This may be due to a more systematic sampling and

more areas covered (see Fig. 2B).

In terms of relative density per plot Sonneratia alba was the most dominant, being present in

5 out of 7 plots followed by Rhizophora apiculata occurring in 4 out of 7 plots (see Fig. 6).

Rhizophora mucronataoccurred in3 out of 7 plots, R. stylosa and Avicennia marina in 2 out of

7 plots. All the rest were found in only one plot (See Fig. 6).

In terms of tree size, Sonneratia alba were the largest mangroves reaching maximum

diameter at breast height of 102 cm with average BA of 1292.7cm2,while the largest

mangrove associate was Pongamia pinnata with maximum DBH of 71.6 cmwith average BAof

18502.7 cm2(see Table 5).


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Noteworthy was the hybrid of Rhizophora x lamarckii hybrid between the reforested area and

the natural forest. Also, single plants of Bruguiera gymnorrhiza and Bruguiera cylindrica were

found at the edge of the navigation highway.

Figure 6. Relative density of mangrove species in Dipatlong.


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surveyed plots in Dipatlong.

Species Min DBH (cm) Max DBH (cm) Average DBH Average BA (cm2)

Rhizophora apiculata 6 24.5 6.7 3978.3

Sonneratia alba 4 102 20.3 1292.7

Rhizophora mucronata 4 13 6.9 44.1

Rhizophora stylosa 4.5 7.5 4.6 28.6

Aegiceras corniculatum 4 5 3.7 16.1

Avicennia marina 5 17 10.3 103.9

Excoecaria agallocha 8 26 15.9 221.4

Xylocarpus moluccensis 5 18 11.4 143.8

Pongamia pinnata 30.2 71.6 45.1 18502.7

Lincod. This is one of the two most diverse sites with 21 mangrove species but also the most threatened with fishponds occupying what used to be mangrove forest (see Fig. 7). The endangered Camptostemon philippinensis was also found here The most abundant species were Sonneratia alba, Avicennia marina and Rhizophora mucronata. There were also monospecific patches of Xylocarpus moluccensis, Lumnitzera littorea, and Excoecaria agallocha. Biggest trees were Sonneratia alba with maximum DBH of 51.9 cm and average BA of 327.0 cm2 (see Table 6).

Figure 7. Relative density of mangrove species in Lincod.


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Lincod.

Species Min DBH (cm) Max DBH (cm) Average DBH

(cm) Average BA

(cm2)

Aegiceras corniculatum 4 15 7.1 505.1

Avicennia lanata 4.80 36 16.6 145.4

Avicennia marina 5 41.10 15.1 357.8

Avicennia officinalis 5 16.50 8.7 345.6

Bruguiera cylindrica 5.0 5.0 5.00 19.63

Bruguiera parviflora 4 11 7.5 601.7

Camptostemon philippinensis 5.0 8.0 6.50 34.95

Ceriops decandra 6 6 only one tree 28.3

Excoecaria agallocha 5 36.00 14.1 148.8

Lumnitzera littorea 6 42.00 19.3 497.8

Rhizophora apiculata 4 23 10.6 355. 8

Rhizophora mucronata 4 22 8.4 203.0

Rhizophora stylosa 6 13.60 9.5 76.7

Sonneratia alba 4 51.90 20 327.0

Xylocarpus granatum 5 21 11.9 84. 9

Xylocarpus moluccensis 6.70 11 8.9 65.2

Avicennia officinalis 8.0 8.0 8.00 50.27

Sonneratia alba 8.0 38.0 23 592.19

San Vicente. This is the other most diverse site with 21 species of mangroves and the most

well protected forest in the whole Bay. Most abundant species is Rhizophora apiculata (see

Figure 8. Relative density of mangrove species in San Vicente.


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Fig. 8). Biggest trees were Rhizophora stylosa with maximum DBH of 31.5 cm and average BA

of 683.3 cm2 andSonneratia alba with maximum DBH of 30 cm and average BA of 555.3 cm2

(see Table 7). This is because most of the trees measured were located in the fringes of the

forest since it was difficult to get inside (see Fig. 8).


San Vicente.

Species Min DBH (cm) Max DBH (cm) Average DBH

(cm) Average BA

(cm2)

Aegiceras floridum 9.5 9.5 only one tree 70.9

Avicennia marina 4 14.5 6.4 201.5

Avicenniao fficinalis 4.1 10.1 6.7 493.7

Avicennia lanata 10.1 15.5 12.8 134.4

Ceriops decandra 4 9.5 5.7 29.1

Ceriops tagal 4.7 4.7 only one tree 17.4

Osbornia octodonta 4 5 4.5 16.1

Rhizophora apiculata 4 9.6 7.2 79.9

Rhizophora mucronata 4.5 14.1 7.6 161.6

Rhizophora stylosa 4 31.5 7.4 683.3

Rhizophora x lamarckii 5 21.5 12.2 969.3

Scyphiphora hydrophyllacea 4.5 4.5 only one tree 15.9

Sonneratia alba 4.5 30 11.3 555.3

Cabawan. This site along the Abatan River was visited during the second sampling to verify

the presence of Bruguiera sexangula although as was pointed out, this was already “outside”

of Maribojoc Bay (see Fig. 9). Two new records were also found: the mangrove Heritiera

littoralis and the mangrove associate Hibiscus littoralis. Largest trees in the plots surveyed

were Bruguiera parviflora reaching 26 cm in dbh (Table 8).


Cabawan.

Species Min DBH (cm) Max DBH (cm) Average DBH (cm) Average BA (cm2)

Bruguiera parviflora 15.5 27.2 22.03 399.94

Bruguiera sexangula 8.1 27.0 13.83 196.56

Heritiera littoralis 10.1 12.2 11.23 99.70


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Figure 9. Relative density of mangrove species in Cabawan.

Threats

Several threats to the mangrove forest of Maribojoc Bay were seen. The primary threats are

the continuing expansion of fishponds and settlements, leading to dredging and garbage.

Minor threats are cutting and girdling, pests and diseases.

Conclusions

The Maribojoc mangrove forest is one of the most diverse, if not the most diverse mangrove

forest in the Philippines with 35 species in 15 families, including one hybrid and excluding

mangrove associates. Four of the species four families are in the IUCN (2015) threatened

species list: En - Camptostemon philippinensis (S.Vidal) Becc., NT- Aegiceras floridum Roem.

and Schult., and, Ceriops decandra (Griff.) Ding Hou and V- Avicennia lanata Ridley. The most

common species is Sonneratia alba with mean density of 385 + 37 stems ha-1 while those with

only one stem found in the surveyed plots were Aegiceras floridum, Bruguiera gymnorrhiza

Dredging and garbage. Fishponds in Lincod. Girdled Lumnizera littorea

(maudo) in Upper de la Paz.

Figure 10. Threats seen to the mangroves and forest of Maribojoc Bay.


18

and Xylocarpus rumphii. Among the herbaceous and shrubby species, Nypa fruticans was the

most abundant with a mean cover of 42.0 + 36.3%.

Among the sites, Lincod and San Vicente are the most diverse with 21 species of mangroves,

excluding associates but while San Vicente is the best protected, Lincod is the most

threatened due to fishpond development. It is also the site where three of the threatened

species are found.

Overall, the forest has a moderate regeneration potential of about 50% with seedlings and

saplings of 19 species out of 35 found during the sampling period. No seedlings were seen

for 4 species with saplings and no saplings were seen for 5 species with seedlings. Bruguiera

parviflora had the highest number of seedlings (2605 + 5414 seedlings ha-1) but almost no

saplings were found (1 + 2 saplings ha-1) while Ceriops decandra had the most number of

saplings (902 + 1057 saplings ha-1) but no seedlings were seen.

Recommendations

1. A comprehensive management and conservation plan for the Maribojoc Bay

mangrove forest is urgently needed.

2. In the meanwhile, activities that could be done at the barangay level include:

a. Enhancement planting of disappearing species and threatened species (marked

with asterisk). The list below shows priority species and their seed/seedling

source:

Species Local Name Seed/Seedling Source

Aegiceras floridum Roem. and Schultes* Tinduk-tindukan/ San Vicente

Avicennia lanata Ridley* Lincod

Bruguiera cylindrica (L.) Blume Pototan-lalake Dipatlong

Bruguiera gymorhiza (L.) Lamk. Busaing San Vicente

Bruguiera parviflora Wight & Arnold ex Griffith Upper de la Paz, Cabawan

Bruguiera sexangula (Lour.) Poir. Pototan Cabawan

Camptostemon philippinensis (S.Vidal) Becc.* Gapas-gapas Lincod

Ceriops decandra (Griff.) Ding Hou* Lapis-lapis All sites

Lumnitzera littorea (Jack) Voigt Tabao/Maudo Upper de la Paz

Scyphiphora hydrophyllacea Gaerten. f. Nilad San Vicente

Xylocarpus rumphii( Kostel) Mabb. Tabigi/Piagau San Vicente

3. Regular inventory of existing species and monitoring of threats. Mangrove species that

were not found in this survey and are put on the watch list for monitoring are:

a) Acanthus ilicifolius L.,

b) Sonneratia caseolaris (L.) Engler

c) Sonneratia ovata Backer


19

4. Awareness campaign on the importance of mangroves and their role in livelihood

provision.

5. Initiation of new (bird watching) and strengthening of existing ecotourism (e.g., firefly

tour) and other livelihood activities dependent on mangroves.

Acknowledgements

We thank the local government units for their support during the surveys. We are especially

grateful for the services of Ronald Tugap during the second sampling who served both as our

guide and boatman. Funding from the Foundation for the Philippine Environment is most

appreciated.

References

Calumpong, H.P. and E.G. Meñez. 1997. Field Guide to the Common Mangroves,

Seagrasses and Algae of the Philippines. Bookmark, Inc., Manila.197 pp.

English S.A., C.R. Wilkinson and V.J. Baker. 1997. eds. Survey Manual for Tropical Marine

Resources, 2nd ed. Townsville, Australia: Australian Institute of Marine Science.

http://www.vliz.be/vmdcdata/mangroves/. MassóiAlemán, S., C. Bourgeois, W. Appeltans,

B. Vanhoorne, N. De Hauwere, P. Stoffelen, A. Heaghebaert& F. Dahdouh-Guebas,

2010. The Mangrove Reference Database and Herbarium.Plant Ecology and

Evolution 143(2): 225-232.

IUCN.2015. The IUCN Red List of Threatened Species. Version 2015-4.

<http://www.iucnredlist.org>. Downloaded on 29JUNE 2016.

Primavera, J.H. and Sababada, R.B. 2012.Beach Forest Species and Mangrove Associates in

the Philippines.Tigbauan, Iloilo: SEAFDEC Aquaculture Department. 154 pp.

Primavera, J.H. and Sababada, R.B., Lebata, M.J.H.L. and Altamirano, J.P. 2004. Handbook

of Mangroves in the Philippines – Panay. Tigbauan, Iloilo: SEAFDEC Aquaculture

Department. 106 pp.

PROCESS- Bohol. 2013. Reassessment of Community-Managed Mangrove Forest

Ecosystems in Maribojoc Bay Project. Report.Foundation for the Philippine

Environment.

SUML. 1997. Biophysical Resource Assessment: Coastal and Upland Areas of Abatan

Watershed, Bohol. Report. Foundation for the Philippine Environment.

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http://www.iucnredlist.org/

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